The values are usually found in the product sustainability reports of the respective brands.

The CO2e is the combination of Static emissions and variable emissions. Emissions from the production (usually over 80%) and transport are consider static emissions as the resources have been already used when you purchase that product, where as variable emission is the use phase emission, depends on number of years you consume that product.

Lifetime of a particular devices is the number of years that the manufacturer has specified in the product document e.g. CO2e value is 339 Kg of CO2e for 4 years of use phase.